Various technologies and standards have been developed with regard to mobile terminals and mobile communication systems (see Patent Documents 1-3, Non-Patent Documents 1-2).
The next-generation (3.9G) mobile communication standard, known as LTE (Long Term Evolution), prescribes a radio access method in which uplink communication employs a single carrier frequency division multiple access method (SC-FDMA: Single Carrier (SC)-Frequency Division Multiple Access) while downlink communication employs an orthogonal frequency division multiple access method (OFDMA: Orthogonal Frequency Division Multiple Access).
The OFDMA method employed in downlink communication is a digital modulation-demodulation method which multiplexes a plurality of carriers, called subcarriers, by use of orthogonality of frequency. The OFDMA method is superior in resistance to fading and multi-path interference.
On the other hand, the SC-FDMA method employed in uplink communication is similar to the OFDMA method but different from the OFDMA method in terms of the persistency of carriers allocated to users. Compared to the OFDMA method, the SC-FDMA method is expected to improve power efficiency. In the LTE standard, radio resources in uplink communication are divided with respect to a frequency axis and a time axis, so that divided radio resources are allocated to users.
The LTE standard prescribes that a mobile terminal issues a reception intensity measurement report so as to trigger handover. The LTE standard defines Events A1-A5 as reception intensity measurement reports with regard to the same frequency. In particular, a mobile terminal transmits a report of Event A3 triggering handover when the reception intensity of a neighboring sector, measured by the mobile terminal, exceeds the reception intensity of a sector currently conducting communication. The 3GPP standardization organization (see Non-Patent Document 1) prescribes that a report of Event A3 be transmitted in accordance with the following conditional expression.Mn+Ofn+Ocn−Hys>MS+Ofs+Ocs+Off 
where parameters are defined as follows.
Mn: Reception intensity of a neighboring sector
Ofn: Offset value regarding the frequency band utilized by a mobile terminal
Ocn: Offset value regarding the neighboring sector
Ocs: Offset value regarding a sector currently conducting communication
Hys: Hysteresis
Off: Offset value inherent in Event A3
The conditional expression is easily satisfied when the offset value Ocn of a neighboring sector increases. In contrast, the conditional expression is hardly satisfied when the offset value Ocn decreases. This makes it possible to accelerate or prevent communication handover with a mobile terminal between sectors by changing the offset value Ocn. In this connection, a mobile terminal is notified of a change of the offset value by way of sector notification information of a radio base station or an individual control signal.